This invention relates to a method of constructing the path information of a network management system (NMS). More particularly, the invention relates to a method of constructing the path information of a network management system by collecting data held by network elements (NE) such as transmitters constructing the network, using this data to construct path information which specifies a path that exists in the network, and managing the network.
(a) Shelf
An optical transmission system is constructed by preparing several basic shelves, combining the basic shelves to construct a network element such as a terminal station, repeater station or signal regenerator, and using such network elements to construct the optical transmission system. FIG. 14 is a diagram showing the construction of a high-speed shelf 150, and FIG. 15 is a diagram showing the construction of a tributary shelf 160. The high-speed shelf 150 includes line optical interfaces 151, 152 for interfacing optical transmission lines such as OC-48 (2.4 Ghz) optical transmission lines; a switch 153 for switching paths; and an interface 154 for interfacing the tributary side. The line optical interfaces respectively include O/E converters 151a, 152a for converting optical signals to electric signals; E/O converters 151b, 152b for converting electric signals to optical signals; demultiplexers (DMUX) 151c, 152c for demultiplexing a higher-order signal (an OC-48 optical signal) into three types of signals STS-1, STS-3C and STS-12C; and multiplexers (MUX) 151d, 152d for multiplexing the signals STS-1, STS-3C and STS-12C. The three types of signals demultiplexed by the demultiplexers 151c, 152c are allowed to pass by the switch 153 or are dropped on the tributary side by the switch 153. Further, the switch 153 switches signals STS-1, STS-3C, STS-12C, which have been inserted from the tributary side, in an E (East) or W (West) direction.
The tributary shelf 160 includes tributary-side interfaces 161, 162 for lower-order signals (DS3.times.12 ch, STS-1.times.12, OC-3/3C.times.2 ch, OC-12/12C.times.1 ch); a switch 163; and an interface 164 for interfacing the HS shelf. The tributary-side interfaces 161, 162 respectively include multiplexer/demultiplexers (MUX/DMUX) 161a, 162a for multiplexing the signals STS-1, STS-3C, STS-12C and inputting them to the switch 163, and for demultiplexing signals, which have entered from the switch 163, and outputting the demultiplexed signals; and interfaces 161b, 162b for interfacing an office multiplexer.
(b) LTE, LNR ADM, REG
By combining the high-speed (HS) shelf 150 and tributary (TRIB) shelf 160, it is possible to construct LTE (Line Terminal Equipment) serving as the termination station of an optical transmission line, as shown in FIGS. 16A, 16B, or an LNR ADM (Linear Add/Drop Multiplexer) serving as a repeater (D/I: Drop/Insert), as shown in FIG. 16C. A signal regenerator (REG) can be constructed by having the switch in the HS shelf 150 pass the signals. It should be noted that only the line optical interfaces on one side of the HS shelves in the LTEs of FIGS. 16A, 16B are being used.
(c) Construction of Transmission System
A point-to-point optical transmission system can be constructed by using LTEs, constructed as set for above, as terminal stations (stations A, B) of an OC-48 optical transmission line in the manner shown in FIG. 17. A ring system can be constructed by connecting LNR ADMs in the form of a ring, as illustrated in FIG. 18. Furthermore, a linear ADM system can be constructed by using LTEs as terminal stations (stations A, C) and an LNR ADM as a repeater station (station B), as depicted in FIG. 19.
(d) Frame Format
Information in the above-described optical transmission system is transmitted upon being assembled into an SDH/SONET frame. FIG. 20A is a diagram useful in describing the format of a 155.52 Mbps frame in SDH. One frame consists of 9.times.270 bytes. The first 9.times.9 bytes are section overhead (SOH) and the remaining bytes are path overhead (POH) and payload (PL). The section overhead SOH transmits information (a frame synchronizing signal) representing the beginning of a frame, information specific to the transmission line (information for checking for error at the time of transmission, information for network maintenance, etc.) and a pointer which indicates the position of the path overhead POH. The path overhead POH transmits inter-network end-to-end monitoring information, and the payload PL transmits 150.52 Mbps information.
The section overhead SOH is composed of 3.times.9-byte repeater section overhead, a 1.times.9-byte pointer and 5.times.9-byte multiplexer overhead. As shown in FIG. 20B, the repeater section overhead has bytes A1-A2, C1, B1, E1, F1 and D1-D3. The multiplexer section overhead has bytes B2, K1-K2, D4-D12 and Z1-Z2. The D1-D3 bytes are used in data transmission between repeater sections, and the D4-D12 bytes are used in data communication between multiplexer sections. A 155.52.times.n Mbps frame can be constructed by multiplexing n-number of the frames shown in FIG. 20A. For example, a 622.08 Mbps frame can be constructed by multiplexing four of the frames shown in FIG. 20A.
(e) HS Shelf
FIG. 14 is a diagram showing the construction of the HS shelf, with the focus being on the main signal system. However, an HS shelf is equipped with various units in addition to the units of the main signal system, examples of these other units being an overhead processing unit, a processing unit for interfacing an external device, and a unit for performing monitoring/controlling within the shelf.
FIG. 21 is a diagram showing the construction of an HS shelf which includes these units.
As shown in FIG. 21, the HS shelf 150 possesses an optical transmitter unit 1 and an optical receiver unit 2 as OC-48 optical signal interface units. The optical transmitter unit 1 functions to convert an STS-48 electric signal to an OC-48 optical signal and transmit the latter signal, and the optical receiver unit 2 functions to convert an OS-48 optical signal to an STS-48 electric signal.
A multiplex/demultiplex/TSA function unit 3 is used in the multiplexing and demultiplexing of the STS-48 electric signal. If the HS shelf is used in an LTE device and LNR ADM device, the unit 3 functions to multiplex the STS-12C.times.4 electric signals from the shelf of the lower-order group to the STS-48 electric signal and, conversely, to demultiplex the STS-48 electric signal to the STS-12C.times.4 electric signals. The HS shelf has a STS-1.times.48 TSA (Time Slot Assignment) function as well implemented when multiplexing/demultiplexing is performed.
In addition to the above-mentioned units, the HS shelf has a power supply unit 4, an alarm function unit 5, an interface unit 6 having a function for interfacing an external monitoring system (e.g., a network management system NMS), a control unit 7 for supervising the internal shelf monitoring/control function, and an overhead processing unit 8 for processing the overhead byte OHB of the OC-48 signal. A terminal such as a personal computer is connected to the control unit 7.
In a large-capacity network composed of currently existing SDH/SONET transmitters/wireless units (network elements), a network management system (NMS) for centralized management of these network elements (NEs) is essential. An NMS functions to monitor faults and identify faulty points by acquiring NE device status and line status. In order to implement these functions, path (line) management is vital. Path management includes a function for collecting path information (the order in which NEs constructing a path are connected and cross-connect information within an NE) that has already been set, a path set-up function used when changing and adding on a path, a path-related alarm detection function and a path repair function.
Either of the following two techniques is used to acquire path information in the conventional system: (1) A path from the NMS is established with respect to each NE and the pass set-up information at this time is stored in a database. (2) The cross-connect set-up of each NE and the status of connection of each NE are traced in detail, path information is generated from this data and the information is stored in a database.
However, both of these techniques are manual techniques that require control by the operator. Moreover, a problem arises in terms of processing time. In particular, with technique (1), the fact that paths on the order of tens of thousands of lines must be established when a large-scale network is initially started up means that a great amount of time and labor is required to perform this operation. Technique (2), which extracts cross-connect information from an NE and constructs path information automatically, involves complicated processing and is impractical from the standpoint of processing time.
Further, recent network elements are equipped with a cross-connect function so that path set-up and path change (cross-connect set-up and cross-connect change) within an NE can be performed with ease using a terminal such as a personal computer. Though this capability is convenient, there are instances where an already established path is changed inadvertently to a path having a different arrangement. In such cases it is necessary to generate an alarm promptly and restore the original path set-up. With the prior art, however, the NMS is not adapted to effect restoration automatically upon detecting such an alarm. As a result, the original path set-up cannot be restored in prompt fashion.